Optimizing water management for sustainable use of agricultural lands and water

曼尼托巴省南部的灌溉正在扩大，在这些地区，劣质地下水的盐碱化一直是一个主要问题。无论植物在哪里被灌溉水，植物都会吸收水分，并在根区留下盐分，导致盐碱化。排水系统可以用来去除多余的水，用于清洗根区以下的盐，以减轻盐碱化。然而，传统的排水系统也可能会过度排水，导致宝贵的养分和水分流失。控制排水可用于克服这一缺点。***以前NSERC资助的田间规模研究表明，合理设计和管理的灌溉和排水系统可以显著提高马铃薯产量30%和玉米产量15%。然而，春季融雪期和强降雨期间，主要的养分外流出现在瓦片排水中。使用排水控制结构（DCS）进行控制排水，可以阻止农田内的水，与常规排水相比，可以减少90%的养分流出。使用DCS被认为是减少田间养分输出的最佳管理做法。然而，由于春季地下水位较高，这种做法可能会对土壤的可通行性产生负面影响。拟议的研究将优化控制排水的操作，以保留田地内的水和养分，同时改善交通。DCS还可以促进地下灌溉，其中灌溉水通过DCS应用到地下排水管中。然而，如果根区下面的土壤变得过于干燥，则地下灌溉水向上流动可能受到限制。该研究的数据将用于Hydrus的2D/3D模型，以模拟不同的土壤类型和天气条件，并确定适合地下灌溉的土壤。***短期内的主要目标将是：(1)监测根部区域内的水分和养分流动，以评估地下灌溉/排水系统对作物产量和水质的影响；(2)确定地下水位的最佳深度，既能保证田间作业，又能保持田间的水分和养分；(3)确定在高蒸散期可进行次灌溉的最佳地下水位深度。我将使用NSERC的发现基金来部分支持3名博士、5名硕士和12名理学士学生。农民将受益于产量的提高和田地内更好的养分保留。***长期而言，目标将是优化综合水管理系统，结合地下灌溉/控制排水系统，并为成功实施的选址制定一项协议。长期目标是管理农田内的水和养分，在农场规模上实现农业的可持续性，并最大限度地减少养分流入河流和湖泊。* * * * * * * *

Irrigation is expanding in Southern Manitoba in areas where salinization from poor quality groundwater has been a major problem. Wherever irrigation water is applied to plants, the plants take up the water and leave behind the salts within the root zone leading to salinization. Drainage systems can be used to remove the excess water applied to wash the salts below the rootzone to mitigate salinization. However, conventional drainage systems may also over-drain the field, removing valuable nutrients and water. Controlled drainage can be used to overcome this shortcoming. ***Previous NSERC funded field-scale research showed that properly designed and managed irrigation and drainage systems can significantly improve yield by 30% in potatoes and 15% in corn. However, major nutrient outflows were observed in tile drainage during spring snowmelt period as well as during high intensity rainfall. Controlled drainage using Drainage Control Structures (DCS) that can hold back the water within the field was shown to lower the nutrient outflow by 90% compared to conventional drainage. The use of DCS was found to be a best management practice to minimize nutrient export from the field. However, this practice may negatively impact soil trafficability due to the high water table in the spring. The proposed research will optimize the operation of controlled drainage to hold back the water and nutrients within the field while allowing improved trafficability. The DCS can also facilitate subirrigation where the irrigation water is applied through the DCS into the subsurface drains. However, the upward flux of subirrigated water may be restricted if the soil beneath the root zone becomes too dry. The data from this research will be used in Hydrus 2D/3D model to simulate different soil types and weather conditions and identify soils suitable for subirrigation.***In the short term, the main objectives will be to (1) monitor the water and nutrient movement within the root zone to assess the impact of subirrigation/drainage systems on crop yield and water quality; (2) determine the optimum depth of the water table that will still allow field operations while conserving the water and nutrients within the field; (3) determined the optimum depth of water table that will allow subirrigation during periods of high evapotranspiration. I will use the NSERC Discovery grant to partially support three PhD, five MSc, and twelve BSc students. Farmers will benefit from improved yields and better nutrient retention within the field.***In the long term, the objective will be to optimize the integrated water management systems combining subirrigation/controlled drainage systems and develop a protocol for site selection for successful implementation. The long-term goal is to manage the water and nutrients within the field and attain agricultural sustainability at the farm-scale and minimize the nutrient outflow into the rivers and lakes. ********